1. Field of the Invention
The present invention relates to induction foil cap sealers and more particularly, to an induction foil cap sealer with a monitoring system for monitoring the sealing operation.
2. Description of the Prior Art
Induction foil cap sealers are well known. Referring to FIG. 1, a prior art induction foil cap sealer includes induction head 100 that includes a plurality of field coils 120. In operation, field coils 120 receive an electrical current that causes the development of magnetic fields that project away from field coils 120. The projected magnetic fields are schematically shown as circular lines surrounding field coils 120 for illustration purposes only. The magnetic fields projecting from field coils 120 are used for sealing a cap onto an opening of a bottle in the following manner.
Cap 104 is mechanically coupled to the opening of bottle 102 and placed under induction head 100. Due to the mechanical coupling between cap 104 and bottle 102, metallic foil 106, which is received in cap 104, is pressed between the end of cap 104 and the sealing edge of the opening of bottle 102. Included inside cap 104 is polymer sealing film 112, which is interposed between metallic foil 106 and the opening of bottle 102. Optionally, wax layer 108 and pulp board liner 110 are also included in cap 102 and sandwiched between metallic foil 106 and the closed end of cap 104.
To effect the seal, magnetic fields that project from field coils 120 permeate cap 104 and cause foil 106 to heat up. The heat so generated causes polymer sealing film 112 to melt and thus seal metallic foil 106 to the opening of bottle 102. As a result, a hermetic seal between metallic foil 106 and bottle 102 is obtained which can survive the removal of cap 104. If optional wax layer 108 is used, the generated heat melts wax layer 108 further enhancing the hermetic effect.
Induction head 100 may assume any number of shapes depending on the type of cap used. FIGS. 2A-2C illustrate three examples of induction heads.
Referring to FIG. 3, which illustrates a top down view of an example induction foil cap sealer system 130, in a typical induction sealing operation, a cap 104 and metallic foil 106 are mechanically coupled to each of a series of bottles 102 (this operation is not shown in the Figure) and the bottles are transported on a conveyor belt 134 under an induction head 100. Induction head 100 is included as part of induction sealer 132 and is positioned over conveyor belt 134. As the bottles are transported on the conveyor belt under the induction head, the bottles are subjected to induction heating as described above, thereby forming a hermetic seal.
In general, before sealed bottles leave a manufacturer's plant, it is commercially important that a hermetic seal of good quality be formed on each bottle. For example, when the content of a container is medicine, a misapplied foil 106 may cause a consumer to suspect product tampering, thereby returning the product to the manufacturer and affecting manufacturer costs. Numerous factors can affect the quality of a hermetic seal. For example, a bottle may be missing foil 106, thereby never forming a hermetic seal or a cap may be misapplied when mechanically coupled to a bottle (e.g., skewed or not tightened), thereby causing the metallic foil to not completely contact and seal to the bottle opening. Similarly, a hermetic seal may be incorrectly formed as a result of the bottle being under or over heated, for example. Under or over heating may be the result of conveyor belt 134 moving too slow or too fast or insufficient power being supplied to induction head 100. Notably, a system operator can constantly oversee the sealing operation of foil cap sealer system 130 and physically inspect each bottle, all in an attempt to ensure that the system is properly operating and that quality hermetic seals are being formed. However, this is labor intensive and costly and it may be difficult for an operator to even detect a problem when it occurs.
In addition, because the sealing operation is a mechanical and automated process, system failures can occur. For example, bottles can stall under the induction head due to a conveyor belt stopping or bottles jamming and as a result, become overheated. Similarly, the system may overheat. Again, a system operator can constantly oversee the sealing operation, but this is costly.
Accordingly, it is desirable to have an automated monitoring system to monitor conditions related to the sealing and system operation of a foil cap sealer system so as to notify an operator of possible problems and to assist that operator in diagnosing the problems.